Qt Documentation

Contents

QMetaDataWriterControl Class

The QMetaDataWriterControl class provides write access to the meta-data of a QMediaService's media. More...

Header: #include <QMetaDataWriterControl>
qmake: QT += multimedia
Inherits: QMediaControl

Public Functions

virtual ~QMetaDataWriterControl()
virtual QStringList availableMetaData() const = 0
virtual bool isMetaDataAvailable() const = 0
virtual bool isWritable() const = 0
virtual QVariant metaData(const QString &key) const = 0
virtual void setMetaData(const QString &key, const QVariant &value) = 0
  • 31 public functions inherited from QObject

Signals

void metaDataAvailableChanged(bool available)
void metaDataChanged()
void metaDataChanged(const QString &key, const QVariant &value)
void writableChanged(bool writable)

Static Public Members

const QMetaObject staticMetaObject
  • 9 static public members inherited from QObject

Protected Functions

QMetaDataWriterControl(QObject *parent = nullptr)
  • 9 protected functions inherited from QObject

Macros

QMetaDataWriterControl_iid

Additional Inherited Members

  • 1 property inherited from QObject
  • 1 public slot inherited from QObject

Detailed Description

The QMetaDataWriterControl class provides write access to the meta-data of a QMediaService's media.

If a QMediaService can provide write access to the meta-data of its current media it will implement QMetaDataWriterControl. This control provides functions for both retrieving and setting meta-data values. Meta-data may be addressed by the keys defined in the QMediaMetaData namespace.

The functionality provided by this control is exposed to application code by the meta-data members of QMediaObject, and so meta-data access is potentially available in any of the media object classes. Any media service may implement QMetaDataControl.

The interface name of QMetaDataWriterControl is org.qt-project.qt.metadatawritercontrol/5.0 as defined in QMetaDataWriterControl_iid.

See also QMediaService::requestControl() and QMediaObject.

Member Function Documentation

[protected] QMetaDataWriterControl::QMetaDataWriterControl(QObject *parent = nullptr)

Construct a QMetaDataWriterControl with parent. This class is meant as a base class for service specific meta data providers so this constructor is protected.

[virtual] QMetaDataWriterControl::~QMetaDataWriterControl()

Destroy the meta-data writer control.

[pure virtual] QStringList QMetaDataWriterControl::availableMetaData() const

Returns a list of keys there is meta-data available for.

[pure virtual] bool QMetaDataWriterControl::isMetaDataAvailable() const

Identifies if meta-data is available from a media service.

Returns true if the meta-data is available and false otherwise.

[pure virtual] bool QMetaDataWriterControl::isWritable() const

Identifies if a media service's meta-data can be edited.

Returns true if the meta-data is writable and false otherwise.

[pure virtual] QVariant QMetaDataWriterControl::metaData(const QString &key) const

Returns the meta-data for the given key.

See also setMetaData().

[signal] void QMetaDataWriterControl::metaDataAvailableChanged(bool available)

Signal the availability of meta-data has changed, available will be true if the multimedia object has meta-data.

[signal] void QMetaDataWriterControl::metaDataChanged()

Signal the changes of meta-data.

If multiple meta-data elements are changed, metaDataChanged(const QString &key, const QVariant &value) signal is emitted for each of them with metaDataChanged() changed emitted once.

Note: Signal metaDataChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(metaDataWriterControl, QOverload<>::of(&QMetaDataWriterControl::metaDataChanged),
    [=](){ /* ... */ });

[signal] void QMetaDataWriterControl::metaDataChanged(const QString &key, const QVariant &value)

Signal the changes of one meta-data element value with the given key.

Note: Signal metaDataChanged is overloaded in this class. To connect to this signal by using the function pointer syntax, Qt provides a convenient helper for obtaining the function pointer as shown in this example:

connect(metaDataWriterControl, QOverload<const QString &, const QVariant &>::of(&QMetaDataWriterControl::metaDataChanged),
    [=](const QString &key, const QVariant &value){ /* ... */ });

[pure virtual] void QMetaDataWriterControl::setMetaData(const QString &key, const QVariant &value)

Sets the value of the meta-data element with the given key.

See also metaData().

[signal] void QMetaDataWriterControl::writableChanged(bool writable)

Signal a change in the writable status of meta-data, writable will be true if meta-data elements can be added or adjusted.

Macro Documentation

QMetaDataWriterControl_iid

org.qt-project.qt.metadatawritercontrol/5.0

Defines the interface name of the QMetaDataWriterControl class.

© 2021 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.